1. Field of the Invention
This invention relates generally to magnetic recording disk data storage systems and more particularly to such systems having a plurality of surface zones.
2. Description of the Prior Art
Direct access storage devices (DASD), or disk drives, store information on concentric tracks of a rotatable magnetic recording disk. A magnetic head or transducer element is moved from track to track to record and read the desired information. Typically, the transducer element is positioned on an air bearing slider which flies above the surface of the disk as the disk rotates. In some recently proposed disk drives, the slider (xe2x80x9ccarrierxe2x80x9d) rides on a liquid film or bearing on the disk. A suspension assembly connects the slider to a rotary or linear actuator.
When the rotating magnetic disk of a disk drive is brought to a stopped condition, there is no aerodynamic cushion available to float or fly the slider above the surface. To prevent damage to the surface of the magnetic disk when it is not rotating, it is conventional to xe2x80x9cparkxe2x80x9d the slider in a landing zone so that contact with the disk by the slider will not cause any significant damage and will not destroy magnetically recorded data. However, simply parking the slider does not address the possibility that the disk drive might be impacted by a force sufficient to dislodge the actuator from its parked position, and thus move the slider onto the recording surface of the magnetic disk. Accordingly, it is important that the actuator which positions the slider be restricted or otherwise held in its parked position to prevent any scratching of the data recording region of the disk surface by the slider when there is no aerodynamic bearing between them.
Extremely smooth surfaces exist on both the data surface and the air bearing face of the slider. Without the aerodynamic cushion between the slider and the disk surface, the slider will come into contact with the stationary disk surface and stiction may result. Stiction occurs as two very smooth surfaces stick to each other and effectively prevent the removal of one from the other. The stiction forces may be sufficient to prevent the rotation of the disk. However, even if the disk can be rotated, damage almost certainly will occur to the surface of the disk due to the fact that the slider is in physical contact with and is initially stuck to the disk surface as the disk moves relative to the slider.
The slider can be parked in a landing zone or on an unload device such as a ramp. The actuator which moves the slider must be latched to prevent movement of the slider out of the parked position onto the data recording region of the disk.
Examples of latching devices include U.S. Pat. No. 5,363,261 issued Nov. 8, 1994, by Eckberg et al.; U.S. Pat. No. 4,833,550 issued May 23, 1989, by Takizawa et al.; U.S. Pat. No. 5,446,606 issued Aug. 29, 1995, by Brunneret al.; U.S. Pat. No. 5,117,318 issued May 26, 1992, by Immler et al.; U.S. Pat. No. 5,095,395 issued Mar. 10, 1992, by Wakatsuki; U.S. Pat. No. 4,562,500 issued Dec. 31, 1985 by Bygbnes; Japanese Application J1-166385 published Jun. 30, 1989 by Morita; Japanese Application J2-73581 published Mar. 13, 1990 by Okutsu; Japanese Application J4-26969 published Jan. 30, 1992 by Tamayama; Japanese Application J3-132980 published Jun. 6, 1991 by Sasaki; Japanese Application J2-146109 published Jun. 5, 1990 by Kadowaki; and Japanese Application J1-241070 published Sep. 26, 1989 by Morita.
The landing zone area of the disk is roughly textured to prevent stiction between the disk and the slider when the slider is at rest on the disk. An example of this texturing process is shown in U.S. Pat. No. 5,062,021 issued Oct. 29, 1991, by Ranjan et al. Other examples of textured landing zones include U.S. Pat. No. 5,446,606 by Brunner et al issued Aug. 29, 1995, and U.S. Pat. No. 4,907,106 by Yamada issued Mar. 6, 1990, and IBM TDB Vol. 28, No. 1, June 1985, P. 318.
A problem with the textured landing zone is that the bumps of the texturing tend to wear down with use. This is due to the fact that the slider is still in contact with the disk surface for a time as the disk rotates before the slider becomes airborne. Also, when the disk is in the process of stopping, the slider is in contact with the landing zone for a time before the disk comes to a complete stop. AS the bumps become worn away, stiction between the slider and the disk is more likely and this can result in failure of the system. Another problem encountered with the texturing landing zone is that wear between the slider and the textured zone may damage the delicate transducer head. Both of these problems will become more critical in the future as the slider flying height above the disk continues to decrease.
Briefly, in a preferred embodiment of the present invention, a disk drive system comprises a recording disk, a spindle motor for rotating the disk, an actuator for positioning a transducer/slider over the disk surface, and a control device. The disk has a data zone, a takeoff/landing zone (T/LZ) and a parking zone (PZ). The parking zone has a rough textured surface which prevents stiction between the slider and the disk. The takeoff/landing zone has a lightly textured surface.
The control device controls the actuator and spindle motor. During power-up, the slider is initially at rest on the surface of the parking zone. The spindle motor starts to rotate the disk and immediately thereafter the slider is moved to the takeoff/landing zone. The slider remains in this zone until the spindle motor reaches operating speed and the slider is airborne. Then the slider is moved to the data zone for normal operation.
Upon power-down, the procedure is reversed. The slider is moved to the takeoff/landing zone, the spindle motor is powered off and the disk rotation starts to slow. The slider lands on the takeoff/landing zone, making contact with the disk as the disk slows even more. Just before the disk stops rotating entirely, the slider is moved to the parking zone.
A latch mechanism is used to hold the actuator such that the slider is limited to a location proximate both the takeoff/landing zone and the parking zone. A bias spring in the latch automatically forces the slider over the parking zone when no actuator force is applied. This provides protection that no stiction will occur even when an emergency power failure occurs.
For a fuller understanding of the nature and advantages of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings.